Spark-plug tester.



B. A. NARVESON. 1f SPARK PLUG TESTER.

APPLICATION FILED DEC. 25. 1916.

Patented Apr. 30, 1918.

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Specification of Letters Patent.

Patented Apr. 311, 1912..

application led December 26, 1916. Serial No. 13,919.

44appertains to make and use the same.

a testing apparatus for use in ignition systems -of internal combustionengines by means of which faulty plugs maybe instantly detected. ln thisconnection, l insert between the engine or ground and the,

spark plugs, a testing device which provides a series of gapscorresponding to the number of plugs, and in which the correspondingterminals upon one side of the gaps are formed from a single contactplate from which the ground wire extends to the engine. By thisarrangement ground elec- 'A trodes of the plugs are not grounded in theshells of the spark plug as is customary, butthey are insulatedit'rom'the shells, and consequentl the engine casing, and are connectedto t e testing device which in turn is grounded upon the engine.

A further object of this invention is to provide a circuit closingdevice for use in connection with the tester by means of which thelatter lmay be eliminated as a tester under ordinary runnin conditions.'

With the above objects in view and such others as will hereinafterappear, my invention will now be fully set forth and def scribed,referenceV being had to the accomform of thepanying drawings. A

1n the drawings l y Figure 1 is a front elevation of the tester, Fig. 2is a section online 2-2 of Fig. 1, lig. 3 is a vertical-section-*through one spark-plug used'in the system, and

Fig. 4 is adiagrammatic showing of the system including my tester.

Referring more particularly to the draw ings, 1 represents a housing orcasing of any suitable material which consists ot a back plate 2 and anoverhanging topporltion and a depending flange 3. Secured to the back 2is a base 4 of hard rubber or other suitable insulating material inwhich a number of contact heads 5 are mounted, said heads 5 preferablybeing conical in form and terminating in the threaded stems 6 which passthrough the base 4 and are provided at their lower ends with the bindingnuts '7. Threaded into the rear edge of the K base 4 is a plurality ofset screws 8 which pass through vertical slots 9 in the back plate 2'whereby the base 4 may be vertically adjusted in order to properly setthe points of the contact heads 5 in forming the testing gaps. Securedto the top or cover plate 1 is a conductor plate 10 which carries thedepending web 11 and the spaced wall 12, the web 11 and the wall 12providing a longitudinal passageway or slot 18 in which the slidingcontact plate 14 is seated.

rlhe web 11 extends throughout the length of the casing, and is formedalong its loweredge into a plurality of spark points or terminals 15which are spaced from the points of the contact heads 5, so that aserios of spark gaps are thereby provided. A terminal 16 connected tothe plate 10 provides a means for continuing a ground wire to the engineor other ground. rl`he slide plate 14 is held in elevated position inits slideway 13 by means of the manipulating device 17 entered throughthe casing and, supporting the plate 14, -is directed to control thelatter so that it may be carried into contact with all of the heads 5when the device is not in use as a tester, so that the How ot currentmay not be interrupted by the gaps of the tester when it is notnecessary.

llhe front ot the casing 1 is closed by means of a glass plate 18 whichrests in a groove in the base 4 and has its upper edge engaged betweenthe Harige 3 and the forward edge of the plate 10.

1n interposing the tester between the 'spark plugs and the ground, itbecomes necessary to alter the spark plug structure by eliminating theground terminals and carrying both of the spark terminals to bindingposts upon the outer end of the plug. Thus,

in one instance, the lugs shown in Fig. 3

celain 22 is inserted upon the insulating washer 23. The lower end ofthe shell is annually bored to carry the expansion joint 2J: and theporcelain 25 which in turn, is provided with the parallel passages 26.Extending through the passages 26 and the porcelain 22 are theelectrodes 27 and 28, the upper or outer ends of the electrodes 27 and28 being carried to the binding posts 29 and 30 respectively'. Thus, onebindin post will be connected to the Acoil box an the other binding postwill be connected to a corresponding contact head in the tester casing,and the current thence passes to the ground through the web 11.

The diagram of Fig. 4 shows the method of connecting the plug and testerin the ignition circuit. Only one of the plugs is vshown in the circuit,as an explanation of this circuit will obviously explaln all o the plugcircuits. A wire 8l from the coil box, magnetic or other current source(not shown) is connected to the binding post 29.

The current passes thence through the electrode 27, thence to 'theelectrode 28 and passes then to the binding post 30, and by means of thewire 32 is connected to the binding screws 7 to the electrodes orcontacts 5. The current jumps the gap between the electrodes 5 and thecorresponding points l5 of the web ll and then by means of the wire 33is grounded in an obvious manner.

The adjustment of the gaps between the electrodes 5 and the points 15 isobvious through the manipulation of the set screws 8, and it is alsoobvious that when it is desired to eliminate the gap of the testingdevice so that the iow of the current is un! interrupted, the plate 13is lowered so that it spans all of the contacts or electrodes 5, and thetesting device becomes essentially a groundin device.

What I c aim as my invention is l. A testing device for ignitionsystems, comprising a casing, a plurality of insulated electrodes in thecasing, a continuous plate mounted in the casing and having acorresponding pluralit of points forming spark gaps wlth the e ectrodesand a plate for spanning the gaps to simultaneously eliminate them.

2. A testing device for ignition systems comprising a casing, aplurality of insulated electrodes in the casing, and a continuous platemounted in the casing and having a corresponding plurality of pointsforming spark gaps with the electrodes, a common means for adjusting thegaps and means for instantaneously spanning all of the gaps to eliminatethem.

3. A testing device for ignition systems comprising a casing, aplurality of insulated electrodes in the casing, a continuous platemounted in the casing, and having a corresponding plurality of pointsforming spark gaps with the electrodes, a common means for closin thegaps and a slide plate associated wit the contlnuous plate and adaptedto be moved into contact with all of the electrodes to close all of theaps.

In testimony whereof, I a x my signature, in the presence of twowitnesses.

BERNARD A. NARVESON.

Witnesses:

M. A. WELLES, WILLARD A. RossMAN.

